圆管内水中碳酸钙颗粒趋壁沉积数值模拟

Numerical simulation of calcium carbonate particle deposition in circular tube

采用雷诺应力模型和拉格朗日方法,研究水平圆管内碳酸钙颗粒析出后的趋壁沉积行为。研究发现,二维建模下采用Fluent计算流场脉动速度偏大,又由于颗粒沉积是三维上的不规律运动,所以采用二维模型模拟颗粒沉积并不准确。文中对碳酸钙颗粒沉积进行三维模拟,比较脉动速度模拟结果,证明三维模拟结果优于二维模拟结果,且在近壁区内十分接近DNS结果。在此基础上,模拟不同粒径(颗粒弛豫时间0.4—10)碳酸钙颗粒的沉积速度,结果与文献中实验和模拟结果符合良好,发现水中涡扩散影响区和颗粒惯性影响区分界对应的颗粒弛豫时间(文中约为4)小于气体中的分界(10—100)。

The calcium carbonate particle deposition behavior in water in horizontal circular tube was simulated based on Reynolds Stress Model （RSM） and Lagrangian method. The fluctuation velocity of flow field calculated by Fluent is higher under two dimensional （2D） modeling. And the particle deposition is a random motion in three dimensions （3D）. So the 2D simulation is inaccurate, and the three dimensional （3D） simulation of calcium carbonate particle deposition was made. The comparison of the fluctuation velocity data shows that the 3D simulation result is superior to the 2D simulation result, and the 3D simulation data in the near-wall region is very close to the Direct Numerical Simulation （DNS） data. On that basis, the deposition velocities of calcium carbonate particles of different diameters （particle relaxation time is 0.4-10 ） were simulated. The result shows that the experimental data of literatures and simulation data are in good agreement. The particle relaxation time corresponding to the boundary between eddy diffusion affected area and particle inertia affected area in water （ about 4 in this paper） is less than that in gas （10-100）.